Ellendale climate

Ellendale Frost Dates and Growing Season

NOAA 1991-2020 normals for Ellendale, 0.9 km from Ellendale, elevation 1455 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ellendale. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around May 4 and the first fall freeze around October 2, a growing season of about 149 days.

Median at 36°F
last May 14, first September 24
Median at 32°F
last May 4, first October 2
Median at 28°F
last April 27, first October 12

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 28May 22May 19May 16May 14May 11May 8May 5May 1
32°FMay 17May 12May 9May 6May 4May 2Apr 30Apr 27Apr 22
28°FMay 9May 5May 1Apr 29Apr 27Apr 24Apr 21Apr 17Apr 14
24°FMay 1Apr 27Apr 23Apr 20Apr 17Apr 15Apr 12Apr 9Apr 5
20°FApr 23Apr 18Apr 15Apr 12Apr 9Apr 7Apr 4Apr 2Mar 27
16°FApr 15Apr 10Apr 7Apr 4Apr 2Mar 31Mar 27Mar 21Mar 15

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FSep 14Sep 17Sep 20Sep 22Sep 24Sep 27Sep 29Oct 1Oct 5
32°FSep 21Sep 24Sep 27Sep 30Oct 2Oct 4Oct 7Oct 11Oct 15
28°FSep 28Oct 2Oct 5Oct 8Oct 12Oct 14Oct 17Oct 21Oct 25
24°FOct 5Oct 12Oct 15Oct 19Oct 22Oct 24Oct 27Oct 30Nov 3
20°FOct 15Oct 22Oct 25Oct 27Oct 31Nov 2Nov 5Nov 8Nov 13
16°FOct 25Oct 30Nov 1Nov 4Nov 6Nov 10Nov 12Nov 16Nov 21

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F148142138135132129125121114
32°F167161156153149146143138133
28°F185179175171167163158153147
24°F206199195190186181177172164
20°F223216211207203199195190184
16°F239233228224220215211205200

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
8,501
Cooling degree days, base 65°F
608
Growing degree days, base 40°F
4,374
Growing degree days, base 45°F
3,390
Growing degree days, base 50°F
2,522
Growing degree days, base 55°F
1,761
Growing degree days, base 60°F
1,119

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,65100
February1,40300
March1,12405
April646143
May27631263
June60120511
July15225674
August29176612
September18052336
October590474
November1,03903
December1,48900

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 0.9 km from Ellendale. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00322605 (Ellendale). Public domain.